U.S. patent number 5,310,018 [Application Number 07/992,162] was granted by the patent office on 1994-05-10 for scaffold.
Invention is credited to Jean J. Lahaie.
United States Patent |
5,310,018 |
Lahaie |
May 10, 1994 |
Scaffold
Abstract
An improved scaffold of the lift type having a base and a
working platform on top of the base. Vertical support posts are
provided at the corners of the base passing through guide means at
the corners of the platform. Cooperating drive means on the
platform and posts are used to raise or lower the platform on the
posts relative to the base. A motor on the platform selectively
operates the drive means.
Inventors: |
Lahaie; Jean J. (Cornwall,
Ontario K6J 5E8, CA) |
Family
ID: |
25537989 |
Appl.
No.: |
07/992,162 |
Filed: |
December 17, 1992 |
Current U.S.
Class: |
182/141; 182/113;
182/148; 182/69.6 |
Current CPC
Class: |
B66F
11/04 (20130101); E04G 1/20 (20130101); E04G
2001/244 (20130101) |
Current International
Class: |
B66F
11/04 (20060101); E04G 1/18 (20060101); E04G
1/20 (20060101); E04B 001/20 () |
Field of
Search: |
;182/148,145,63,113,141 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Chin-Shue; Alvin C.
Claims
I claim:
1. A scaffold having in its working position: a base; a working
platform on top of the base; vertical support posts at the corners
of the base, each post comprising a relatively short post base
section fixed to a corner of the base; a plurality of relatively
long, post extension sections; interconnecting means on the free
end of the post base section, and on the ends of the post extension
sections, to rigidly interconnect one or more of the post extension
sections to each post base section and to each other to extend the
support posts; guide means at the corners of the working platform
for the support posts, the guide means comprising a short guide
sleeve fixed on the platform and aligned with a hole on the
platform through which the support post passes; cooperating drive
means on the platform and posts for use in raising or lowering the
platform on the posts relative to the base, the drive means also
supporting the platform on the posts; motor means on the platform,
the motor means selectively operable to operate the drive means to
raise or lower the platform; casters for the scaffold; means in the
bottom of the base, at the corners, for removably receiving the
casters; means in one side of the scaffold for removably receiving
the casters; the casters adapted to be mounted in the bottom of the
base when the scaffold is being used, and in the side of the
scaffold when the scaffold is being stored.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention is directed toward an improved scaffold.
The invention is more particularly directed toward an improved
scaffold of the type having a lift platform.
2. Description of the Prior Art
There is a need, particularly by construction contractors of all
trades, for a relatively small, inexpensive, lift scaffold in the
work place. When repairs, maintenance or installations are needed
in factories or warehouses at low heights it is common to employ
ladders, or regular scaffolds having plank platforms. However it is
difficult and/or awkward to carry or raise the repair, maintenance
or installation equipment and/or needed parts on ladders or
scaffolds. It is known also to use hydraulic lifts to raise a
working platform. These hydraulic lifts are usually mobile,
compact, and efficient but they are very expensive to purchase.
SUMMARY OF THE INVENTION
It is the purpose of the present invention to provide a small,
portable scaffold, having a lift platform, that is quite
inexpensive compared to known hydraulic lifts.
It is another purpose of the present invention to provide a
scaffold having a lift platform that can be easily and compactly
stored when not needed, and easily set up and operated when
needed.
It is a further purpose of the present invention to provide a
small, portable scaffold that is quite stable in the elevated
position while working at low heights.
In accordance with the present invention the improved scaffold has
a base with a platform on top of the base. Vertical support posts
extend up from the base and the platform is guided on the support
posts. Post extension sections are provided to lengthen the support
posts as needed. Cooperating drive means on the support posts and
platform are used to raise or lower the platform on the posts
relative to the base. The cooperating drive means preferably
comprise a rack and pinion system operated by a motor on the
platform.
Scaffolds with lift platforms having extendable posts and employing
a rack and pinion system to lift the platform on the posts are
known as shown in U.S. Pat. Nos. 4,294,332 and 5,102,179 by way of
example. However these known scaffolds are often large and
cumbersome to set up and to store as exemplified by the scaffold in
U.S. Pat. No. 4,294,332. In addition, these known large scaffolds
often employ planks in the platform which can become lost when the
scaffold is stored. When the known scaffolds are compact and
relatively easy to set up, as exemplified by U.S. Pat. No.
5,102,179, they are quite unstable because they do not have a
stable base. Scaffolds without a stable base require stabilizing
means such as cables.
The scaffold of the present invention is quite compact and stores
in a small space when not needed. The working platform forms an
integral part of the scaffold and does not become lost when the
scaffold is stored. The post extension sections are also safely
stored. The scaffold can be stored on its side, taking up little
space. The scaffold is provided with a base forming a stable
foundation for the platform when it is raised. The use of a base
eliminates or at least minimizes the need for stabilizing
means.
The scaffold of the present invention is provided with movable
casters allowing it to be easily removed from storage where it is
stored on its side and wheeled to where it is needed. At the work
site, two workers can easily turn the scaffold on its bottom, and
reposition the casters if needed. The post extension sections are
removed from storage in the base of the scaffold and set out on the
platform. A worker on the platform interconnects a first set of
post extension sections to the vertical support posts on the base
and, operating a motor to run the drive means, raises the platform
from the vertical support posts onto the post extension sections to
elevate the platform.
A protective guard rail is provided about the platform. The
platform, in addition to a plurality of post extension sections,
also carries the tools and equipment needed by the worker on the
platform. The worker adds post extension sections as needed, to
lengthen the support posts. It is not contemplated that the
platform is raised very high. The greatest height for a platform
six to eight feet square would be about thirty feet. The platform
is stable at this low height. If a larger platform were used, it
could be raised to a greater height.
The invention is particularly directed toward a scaffold having, in
its working position, a base and a working platform on top of the
base. Vertical support posts are provided at the corners of the
base. Guide means are provided at the corners of the working
platform for the support posts. The scaffold has cooperating drive
means on the platform and posts for use in raising or lowering the
platform on the posts relative to the base. The drive means also
support the platform on the posts. Motor means are provided on the
platform, selectively operable to operate the drive means to raise
or lower the platform.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the scaffold in a lower working
position;
FIG. 2 is a perspective view of the scaffold in an upper working
position;
FIG. 3 is a cross-section view of the scaffold taking along line
3--3 in FIG. 1;
FIG. 4 is a detail elevation view of one corner of the base of the
scaffold;
FIG. 5 is a detail top view of two corners of the base of the
scaffold with a portion of the base floor removed at one of the
corners;
FIG. 6 is a bottom view of the platform of the scaffold; and
FIG. 7 is an elevation view of the scaffold in its stored
position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The portable scaffold 1 of the present invention, as shown in its
working position in FIGS. 1 to 3, has a base 3 and a working
platform 5 above the base 3. The scaffold 1, also has vertical
support posts 7, preferably one at each corner 9 of the base 3.
Guide means 11 are provided at each corner 13 of the platform 5
through which the support posts 7 pass. The platform 5 carries a
motor 15, as shown in FIG. 3. The scaffold 1 has cooperating drive
means 17, 19 on the platform 5 and support posts 7 respectively to
raise or lower the platform 5 on the posts 7 relative to the base
3. The motor 15 selectively operates the platform drive means 17 to
raise or lower the platform 5.
In more detail, the base 3 has a floor 21, preferably square in
shape, with relatively low side walls 23 at the outer edge of the
floor 21 that extend upwardly. Adjacent each corner 9 of the base
3, as shown in FIGS. 4 and 5, a short post base section 25 of a
post 7 is fixed at its bottom to the floor 21. The post base
section 25 preferably has a square cross-section and has a socket
27 in its top end 29. The socket 27 has a square cross-section.
Braces 31 can connect between the sides 33, 34 of the post base
section 25 adjacent the corner 9 and the side walls 23 to firmly
anchor the post base section 25. A vertical rack section 35 is
provided on one inner side 37 of the post base section, centrally
located thereon. The rack section 35 is securely fixed to the post
base section 25 and forms part of the cooperating drive means
19.
An opening 39 is provided in the bottom of post base section 25 in
each corner, aligned with an opening 41 in the floor 21. The
opening 39 receives the mounting post 43 of a caster 45. The
casters 45 permit the scaffold 1 to be easily moved about in its
working position.
The platform 5, as shown in FIGS. 1 to 3, also has a floor 47 and
low side walls 49 about its outer edge that extend both upwardly
and downwardly from the floor. Guide means 11 in the form of a
short square sleeve 51 as shown in FIGS. 4 and 5 is provided on the
platform floor 47 adjacent each corner 13. These guide sleeves 51
are aligned with the post base sections 25 on the base 3. The post
base sections 25 extend through openings 53 in the floor 47 and
through the sleeves 51. Each sleeve 51 has a slot 55 on an inner
side for accommodating the rack section 35 on the post base section
25.
The drive means 17 on the platform 5, as shown in FIG. 6, includes
a pinion gear 61 adjacent each opening 51 under the floor 47. Two
pinion gears 61 on one side of the platform are mounted on the ends
of a first drive shaft 63 adjacent the inner side of the two
openings 51 on the one side. The first drive shaft 63 is mounted
via brackets 65 to the bottom of floor 47. The two pinion gears 61
on the opposite side of the platform are mounted on the ends of a
second drive shaft 67, that is parallel to the first drive shaft
63, and is adjacent the inner side of the other two openings 51 on
this other side. The second drive shaft 67 is also mounted via
brackets 69 to the bottom of the floor 47. The motor 15 is mounted
centrally under the floor 47. The output of the motor 15 is
connected via a gear box 71 to a main drive shaft 73. The ends of
main drive shaft 73, which extend transversely to the first and
second drive shafts 63, 67, are connected via bevel gears 79, 81 to
bevel gears 83, 85 fixed on the first and second drive shafts 63,
67. The main drive shaft 73 is mounted via brackets 87, 89 to the
bottom of the floor 47. Operation of motor 15 will rotate the
pinion gears 61 via the drive shafts 63, 67, 73 and the bevel
gears.
A guide roller 95 is mounted on the underside of the floor 47 of
the platform at each corner 13 via brackets 97 as shown in FIGS. 4
and 5. The guide roller 95 at each corner is adjacent the outer
side of the opening 51 at that corner, opposite the pinion gear 61
at that corner.
The platform 5 carries a plurality of support post extension
sections 101 as shown in FIGS. 1 to 3. Preferably, the extension
sections 101 are short enough to fit on the floor 47 of the
platform 5. Each extension section 101 has a square cross-section,
a socket 103 at one end 105 and a connecting pin 107 at the other
end 109 as shown in FIG. 4. The extension sections 101 are
preferably tubular to decrease their weight. The sockets 103 are
dimensioned to snugly receive the connecting pins 107 on other post
extension sections 101. Each extension section 101 has a rack
section 113 extending the length of one inner side 115 and
centrally located thereon. The rack sections 113 are securely fixed
to the extension section 101 and form part of the drive means
19.
A guard rail 119, made up of guard rail sections 121, 123, is
provided about the top edge 125 of the sidewall 49 of the platform
5. The guard rail sections 121, 123 are pivotally mounted to
brackets 127, 129 respectively on the sidewall 49. The brackets 127
on two opposed sides 131 of the sidewall 49 are slightly higher
than the brackets 129 on the other two opposed sides 133 of the
sidewall. This allows the guard rail sections 121 of the scaffold
to fold over the folded guard rail sections 123 in the storage
position of the scaffold. In the erected position, the guard rail
sections 121, 123 are joined together by suitable means (not shown)
to maintain them in the erected position about the floor of the
platform.
The motor 15 is electric. An on-off switch operates the motor. The
switch can be mounted in a control pad 141 that is connected to the
motor by a flexible cable 143 as shown in FIGS. 1 to 3. The pad 141
can clip onto the guard rail 119. An extension cord 145 connects
the motor 15 to a source of electrical power. The extension cord
145 can also supply power to a receptacle 147 in the floor 47 of
the platform 5 so that the worker on the platform can use his
tools. A reverse switch on the pad 141 allows the motor 15 to
operate in either direction. Limit switches are provided on the
platform 5 to stop the motor. A lower limit switch 151 as shown in
FIG. 4 is mounted on the bottom of the platform 5. The limit switch
151 stops the motor 155 when it reaches the bottom end 153 of the
rack section 35 on one of the post base sections 25. The lower
limit switch 151 is located below the pinion gears 61 so that the
gears 61 do not run off the rack sections 35. An upper limit switch
155 is mounted on the sleeve 51 mounted on the floor 47 of the
platform 5. The upper limit switch 155 stops the motor 15 when it
does not sense another post extension section 101. This prevents
the platform from running off the posts 7. If desired an upper and
lower limit switch arrangement could be provided at each post
location.
The scaffold 1 is stored on its side so as to take up less space
when not being used, as shown in FIG. 7. In the storage position of
the scaffold 1, the post base sections 25 of the posts 7 extend up
through the sleeves 51 and guide openings 53 in the platform 5. The
platform 5 is closely adjacent the base 3 and the pinion gears 61
mesh with the rack sections 35 on the post base sections 25 near
their lower ends 153. The guard rail 119 is folded down onto the
platform 5 and the post extension sections 101 are stored on the
base 3 within the base side walls 23 under the platform 5. Suitable
means, such as straps, (not shown) can be provided to prevent the
extension sections 101 from shifting when the scaffold 1 is moved
onto its side in the storage position.
Mounting blocks 161 are provided in one side wall 23 of the base 3
and one side wall 49 of the platform 5 as shown in FIGS. 1 and 5
for receiving the casters 45. The casters 45 can be removed from
the base sections 25 and inserted in the mounting blocks 161 so
that the scaffold can be easily moved while on its side when in its
storage position.
In use, the scaffold 1 is wheeled out on its side on the casters 45
from storage to where it will be used. The casters 45 are removed
from the side of the scaffold at the place of use, the scaffold is
tipped onto its base from its side, and the casters 45 are placed
under the base 3. The guard rail 119 is raised and the motor 15 is
plugged in. The motor 15 is operated to slightly raise the platform
5 on the post base sections 25 via rotation of the pinon gears 61,
allowing access to the post extension sections 101 stored in the
base 3. The extension sections 101 are removed and placed on the
platform 5. The worker stands on the platform 5 and places one
extension section 101 on each post base section 25, via the pin and
socket connection ensuring that the rack section 113 on each
extension section 101 forms an unbroken extension of the rack
section 35 on each post base section 25. The operator again
operates the motor 15 to rotate the pinion gears 61 which travel
smoothly from rack sections 35 to rack sections 113 raising the
platform 5 on the posts 7 above the base 3. The base 3 provides a
solid, secure foundation for the posts 7 and the platform 5 carried
on the posts. To go higher, another set of four post extension
sections 101 is placed on top of the first four post extension
sections 101. When the working height is reached the motor 15 is
stopped and the platform 5 is rigidly supported at this height by
the pinion gears 61 meshing with the rack sections 113. As the
platform 5 is lowered, each uppermost set of four extension
sections 101, that the platform has passed by, is removed from the
next set of extension sections and stored on the platform.
* * * * *